Preheat oven to 450 F. Slice butternut squash in two long ways. Remove seeds. Place squash cut side down (skin side up) on a roasting pan that has been lightly greased with olive oil. Roast for about 30 minutes until tender. Remove squash from pan to cool. Cut side should be golden brown and slightly crispy. In a stockpot, sauté shallot in butter. Scoop flesh from squash being careful not to include any skin, and add to the shallots and continue to sauté for 2-3 minutes. Be sure and include all of the caramelized flesh as it adds a nutty flavor to the soup. Cover with vegetable stock and simmer for a further 5 minutes. Remove from heat. Liquefy using a blender or food processor and return to the cleaned stockpot. Add the white wine and season to taste with sea salt and cayenne pepper. Soup should be a creamy consistency. If it is too thick, add a bit more stock and/or white wine to taste. To serve, ladle into warmed soup bowls and garnish with a drizzle of crème fraîche. Sometimes I drizzle truffle oil and add freshly snipped chives. Other times I like to season the soup with smoked paprika and garnish with crispy sage leaves.